The present invention relates to an arrangement for producing a spun thread from a staple sliver, with a drafting unit comprising a delivery roller pair, also comprising an air jet aggregate arranged downstream of the drafting unit, which air jet aggregate comprises an air evacuation channel, and comprising a cleaning channel arranged to the delivery roller pair and comprising a suction opening.
An arrangement of this type is known in European patent application 1 207 225. In the case of this arrangement, a staple sliver is drafted to a fiber strand, which is imparted its spinning twist in the air jet aggregate. The fiber strand is fed first through an entry channel of the air jet aggregate into a vortex chamber, to which is arranged a fluid device for generating a turbulent airflow around an inlet opening of a yarn withdrawal channel. The front ends of the fibers held in the fiber strand are hereby first fed into the yarn withdrawal channel, while rear, free fiber ends are spread out, seized by the turbulent airflow and twisted around the bound-in front ends already located in the entry opening of the yarn withdrawal channel, whereby a thread with a mostly true twist is formed.
An arrangement of this type permits high spinning speeds, whereby high demands are made above all on the drafting unit arranged upstream of the air jet aggregate. In particular, fiber fly tends to settle on the circumferential surfaces of the delivery roller pair, which rotates especially rapidly. For this reason, a suction opening of a cleaning channel is arranged to the delivery roller pair of the known arrangement, which cleaning channel ensures that the delivery roller pair is kept clear of fiber fly. The above mentioned publication does not specify to which vacuum source the cleaning channel is connected, but it can be seen from the patent figures, that in the case of the air evacuation channel and the cleaning channel, different vacuum sources are provided.
It is an object of the present invention to provide a particularly simple design for the arrangement of the above mentioned type.
This object has been achieved in that the air evacuation channel and the cleaning channel are both connected to the same vacuum source.
It has been shown that the low pressures, which on the one hand are necessary for the air evacuation channel and on the other hand for the suctioning of the delivery roller pair, do not differ from each other to such an extent that they could not be achieved by means of a joint vacuum source, for example, a joint blower. This measure results, from the point of view of the technical design, ill significant spacesaving in an area which is already spatially very narrow, and also to a significant simplification of the production process.
In an embodiment of the present invention it is provided that the cleaning channel runs into the air evacuation channel in the interior of the air jet aggregate. Where the cleaning channel runs into the air evacuation channel, the latter can take the form of a ring channel in this area.
The air jet aggregate usually comprises an entry channel which leads to the vortex chamber, to which entry channel the cleaning channel advantageously extends at least approximately parallel. This permits the vortex chamber arranged downstream of the entry channel, as well as the cleaning channel, to be connected in a simple manner to the air evacuation channel. The suction opening of the cleaning channel can be aligned at a distance from the entry channel against a pressure roller of the delivery roller pair. Tests have shown that the pressure roller of the delivery roller pair is particularly susceptible to fiber fly. The distance mentioned above corresponds for the purpose of the present invention approximately to the radius of the pressure roller.
In a further embodiment of the present invention, further suction openings can be arranged to the driven bottom rollers of the drafting unit in the areas facing away from their respective pressure rollers, which suction openings are also advantageously connected to a joint vacuum source. Thus with one single vacuum source, not only can the air involved in the spinning process be withdrawn from the air jet aggregate, but also the entire drafting unit is kept clean.
These and further objects, features and advantages of the present invention will become more readily apparent from the following detailed description thereof when taken in conjunction with a spinning aggregate shown enlarged and schematically in intersection.